Waste materials that are generated at hospitals, medical clinics or the like may be infectious and require specialized processing prior to disposal of the wastes at a dump site. The accumulating wastes should be stored in a sealed receptacle. Periodically, the accumulated wastes are sterilized such as by exposure to high pressure steam to assure that all infectious organisms are destroyed. The wastes are then transferred to a transportable container for delivery to the dump site. Hauling costs can be reduced by compacting the sterilized waste as it is being transferred to the container. Prior U.S. Pat. Nos. 4,374,491 and 5,084,250 describe a type of waste processor which is capable of performing each of these operations.
Infectious wastes from hospitals or the like may include diverse different objects and materials such as used bandages and tissues, hypodermic needles, specimen containers and hard metal prostheses among other examples. It is preferable that the mixture of diverse different objects be shredded, ground up, pulverized or be otherwise reduced to small fragments. This enables greater compaction of the material and breaks up sharp objects in the waste that can otherwise be potentially hazardous. Shredding or the like also makes it apparent to handlers that the waste has been processed and is now harmless. The fragmented material is also unrecognizable as medical waste by casual observers and thereby avoids needless apprehension by persons who may encounter the wastes.
As heretofore practiced, the fragmentizing operation has complicated the handling of the wastes and added substantially to the costs of processing the wastes. Unloading the sterilized wastes from the sterilizing chamber and reloading the wastes into a shredder or the like and then transferring the material from the shredder or the like to a container requires a significant amount of time and effort.
The last mentioned portion of this effort is avoided by apparatus described in prior U.S. Pat. No. 5,294,412. This prior patent discloses a truck vehicle for transporting sterilized wastes to the dump site which carries a shredder and a compactor on the bed of the truck itself. Waste is unloaded from the sterilizer and deposited in receptacles which, when the specialized truck arrives, are lifted and dumped into the shredder which is carried on the truck. Thus the process continues to require multiple loadings and unloadings of the waste material during the course of the process.
Prior devices for fragmentizing wastes in this particular context require a compromise between efficient high speed operation and the degree of fragmenting that is realized. For example, shredders with large cutting blades that are most suitable for shredding large metal objects produce correspondingly large fragments. Shredders which produce desirably fine fragments do not shred such objects in a desirably efficient manner.
The present invention is directed to overcoming one or more of the problems discussed above.